Organosiloxane polyamide block copolymers

ABSTRACT

Organosiloxane-polyamide block copolymers useful as additives to nylon products providing durable low energy surfaces exhibiting low coefficient of friction and as modified nylon exhibiting excellent bonding to glass are defined as block copolymers containing at least one polyamide block of two or more units of the general formula   WHERE R is an alkylene radical of two to 15 carbon atoms and an organosiloxane block containing two or more units of the general formula R&#39;&#39;aSiO(4 a/2) where a is 1, 2 or 3, and R&#39;&#39; is a hydrocarbyl or halogenohydrocarbyl of one to 18 carbon atoms or a divalent organic radical, at least one R&#39;&#39; being a divalent organic radical linking the siloxane block to the polyamide block.

United States Patent 91 Thompson et a1.

[ 51 Mar. 27, 1973 1 ORGANOSILOXANE POLYAMIDE BLOCK COPOLYMERS [75]Inventors: John Thompson, Barry, Glamorgan; Michael James Owen, Penarth,Glamorgan, both of Wales [73] Assignee: Midland Silicones Limited,Reading, Berkshire, England 22 Filed: Apr. 29,1971

[21] Appl.No.: 138,800

[30] Foreign Application Priority Data 3,487,122 12/1969 Stengle";..260/824 3,457,323 7/1969 Stengle ..260/824 3,341,501 9/1967 Hedrick eta1.... ..,..260/ 824 3,284,156 11/1966 Magat et a1 ..260/824 FOREIGNPATENTS OR APPLICATIONS 1,037,125 8/1958 1 Germany ..260/824 1,915,78910/1969 Germany ..260/824 Primary ExaminerSamuel 1-1. BlechAttorneyRobert F. Fleming, Jr., Laurence R. Hobey, Harry D. Dingman andHoward W. Hermann 1 71 ABSTRACT Organosiloxane-polyamide blockcopolymers useful as additives to nylon products providing durable lowenergy surfaces exhibiting lowcoefficient of friction and as modifiednylon exhibiting excellent bonding to glass are defined as blockcopolymers containing at least one polyamide block of two or more unitsof the general formula ICRN where R is an alkylene radical of two to 15carbon atoms and an organosiloxane block containing two or more units ofthe general formula R' SiQ where a is 1, 2 or 3, and R is a hydrocarbylor halogenohydrocarbyl of one to 18 carbon atoms or a divalent organicradical, at least one R being a divalent organic radical linking thesiloxane block to the polyamide block.

7 Claims, No Drawings wherein R represents an alkylene radical havingfrom two to carbon atoms, and (2) an organo-siloxane block comprising atleast two units of the general formula R' SiQ wherein a has a value ofl, 2, or 3,

and R represents a monovalent hydrocarbon radical, a I

monovalent halogenated hydrocarbon radical or a divalent organic radicalattached to silicon through a silicon to carbon bond, there beingpresent in the organosiloxane block at least one of the divalent organicradicals linking the polyamide block and the organosiloxane block.

The block copolymers of this invention contain one or more polyamideblocks attached to an organosiloxane block through a divalent organicradical. The

copolymers can be of several different configurations depending on thenumber of polyamide blocks attached to the or ganosiloxane block. Intheir simplest form, the copolymers can have the configuration AB inwhich A represents the polyamide block and B the organosiloxane block orthey can be of the type represented by ABA. When more than two polyamideblocks are attached to the organosiloxane' block, the copolymers can berepresented by B(A),,, n being an integer greater than 2.

In the polyamide blocks, the radical R can be any alkylene radicalhaving from two to 15 carbon atoms. Such blocks are derived'bywell-known methods from the polymerization of a lactam orcopolymerization of two or more lactams, and the preferred copolymersare those in which the polyamide blocks are derived from thecommercially known lactams, e.g. epsilon-caprolactam, lauryl lactam ormixtures thereof. Preferably, therefore, R is an alkylene radical havingfive or 1 1 carbon atoms.

In the siloxane block, each R represents the specified divalent organicradical or a monovalent hydrocarbon or halogenated hydrocarbon radicalcontaining one to 18 carbon atoms, for example, an alkyl radical, e.g.the methyl, ethyl, propyl, butyl, nonyl, tetradecyl and octadecylradical, an alkenyl radical, e.g. the vinyl, ally] and methallylradical, an aryl radical, e.g. phenyl, naphthyl, benzyl and tolyl or ahalogenated derivative of the foregoing hydrocarbon radicals such as ahaloalkyl radical, e.g. chloromethyl and trifiuoropropyl andbromophenyl. At least one R radical in the organosiloxane block is adivalent organic radical which serves to link the polyamide segment andthe organosiloxane segment. One of the free valencies of the divalentradical is satisfied by a silicon atom of the organo-siloxane block andthe other by a nitrogen atom of the polyamide block. For mostapplications, the preferred copolymers are those in which at least oneof the R radicals is a divalent organic radical and the remainder aremethylradicals. It is also preferred that the organosiloxane blockscomprise units in which a is 2.

The nature of the linking radical represented by R is not criticaland'will depend on the method employed to prepare the copolymer. Itwill, however, be understood by those skilled in the art that thenature'of the radical should be consistent with the intended applicationof the block copolymer. For example, the radical should not contain anyhydrolytically unstable linkages when the intended application requireshydrolytic stability in the copolymer. Preferably, the divalent organicradicals represented by R can be represented by. the formula in which Xis a divalent organic radical attached to silicon through asilicon-carbon linkage, for example, a saturated or unsaturateddivalent'hydrocarbon radical, a divalent radical composed of carbon,hydrogen and oxygen in which the oxygen is present in the form of ethergroups, or a divalent hydrocarbon radical containing amino groups orsulphur atoms. Preferably X is a divalent hydrocarbon radical oramino-substituted hydrocarbon radical having from three to ll carbonatoms. Examples of R radicals, therefore, include (Win 0 nmumunhu(HllzhNlHHl The block copolymers of this invention can be prepared by anovel process which involves promoting ,or initiating the anionicpolymerization of a lactam employing an organosiloxane having at leastone substituent containing a N-acyl lactam group. or a functional groupwhich is; effective in initiating the polymerization of the lactam.

Included within the scope of this invention, there fore, is a processfor the preparation of an .organosiloxane-polyamide block'copolymercomprising (A) mixing l at least one lactam of the general formulawherein R represents an alkylene radical having from two to 15 carbonatoms (2) at least one organo-siloxand: having at least two units of thegeneral formula R"',,SiO wherein a has a value of 1, 2 or 3 and R'represents a monovalent hydrocarbon radical, a monovalent halogenatedhydrocarbon radical or a radical -XY wherein X represents a divalenthydrocarbon radical, a divalent radical composed of carbon, hydrogen andoxygen in which the oxygen is present in the form of ether groups or adivalent hydrocarbon radical-substituted with amino groups or sulphuratoms, and Y is a radical of the formula wherein R represents analkylene radical having from two to carbon atoms, or Y is a functionalgroup capable of initiating or promoting polymerization of the lactam(I) there being at least one -X'Y radical present in theorgano-siloxane, and (3) a catalyst for the anionic polymerization ofthe lactam, and (B) heating the mixture to a temperature at whichpolymerization of the lactam occurs.

Examples of the lactams which can be employed to prepare blockcopolymers according to the process of this invention are propiolactam,pyrrolidone,

enantholactam, capryllactam, azacycloundecan-Z-one,

lauryl lactam, the preferred lactams being epsiloncaprolactam, lauryllactam or mixtures thereof.

' Theorganosiloxanes employed in the process of this invention are thosehaving at least two units of the general formula R",,SiO wherein a has avalue of 1, 2 or 3 and R' is a monovalent hydrocarbon radical ormonovalent halogenated hydrocarbon radical as defined and exemplified inrespect of R, or is the radical X'Y wherein X and Y are as hereinbeforedefined. At least one R.'" radical in the siloxane should be the X'Yradical and preferably the remaining R' radicals are predominantlymethyl radicals. In the --XY radical, X represents a divalenthydrocarbon radical, a divalent hydrocarbon radical having oxygentherein in the form of ether, that is, -COC linkages or a, divalenthydrocarbon radical substituted with amino groups or sulphur atoms.Examples of X radicals, therefore, are -(CH,);,, 4

CH Preferably X is a divalent hydrocarbon radical or a divalent radicalcomposed of carbon, hydrogen and oxygen in which the oxygen is presentin the form of ether linkages. Most preferably, X represents the (CH or-CH CH(CH radical. The radical Y is the radical in which R representsadivalent alkylene radical having from two to 15 carbon atoms or Yrepresents a functional radical capable of initiating or promoting thepolymerization of the lactam (l). A variety of radicals are known whichfunction to initiate or promote the polymerization of lactams and Y canrepresent any of these. Examples of such radicals include ester, amide,anhydride and halogen-substituted carboxylic acid groups, e.g.

the

(JNH; and U groups, isocyanate I groups and groups containing nitrogendirectly substituted with SCO or -SC H,,,,also urea and thioureaderivatives.

The organosiloxanes can vary from the disiloxane up to the highmolecular weight polysiloxanes depending on the size of copolymermolecule desired or on the relative weights of siloxane and polyamidesegments in copolymer. Methods of making the organopolysiloxanereactants are generally 'well known in the art and are described forexample in British Patent Nos. 769,496, 788,984 and l.,084,855.Organopolysiloxanes havingsubstituted therein the N- acyl lactam groupare prepared by reacting an organosilicon compound containing an Sil-lgroup with an N-aliphatically unsaturated acyl lactam. This reaction iscarried forward in the presence of 'a platinum-type catalyst. TheN-aliphatically unsaturated acyl lactam can be prepared by reaction ofan acyl chloride such as vinyl acetyl chloride with a lactam such asepsiloncaprolactam.

According to the process of this invention, the organosiloxane functionsto initiate the polymerization of thelactam or it forms a nucleus fromwhich one or more polymerized lactam segments can grow. in theperformance of the process, the lactam and the organosiloxane are mixedand anionic polymerization of the lactam is initiated, there beingincluded in the reaction mixture a suitable polymerization catalyst (3).

Such catalysts are well known in the art and include, for example,alkali and alkaline earth metals and the hydrides, hydroxides andcarbonates of such metals with the metals and their hydrides beingpreferred. Polymerization of the lactam can becarried out in bulk or inorganic solvent solution and at temperatures from above about C. to morethan 240C. In general, the only limiting factors with regard to theoperative temperatures are the melting point of the lactam, the desiredpolymerization rate and the thermal stability of the components of thereaction mixture. Most conveniently, the reaction is carried out at atemperature within the range from 1 10 to C.

When polymerization is to becarried out in the absence of a solvent, thelactam and the organosiloxane are preferably mixed at a temperature atwhich the lactam is molten, and the catalyst then added. If desired,however, the lactam, organosiloxane and catalyst can be brought togetherat room temperature and heated, preferably with stirring to atemperature at which polymerization of the lactam takes place. When thereaction is carried out in an 'organic solvent, the preferredsolvents'are the high boilinghydrocarbons, e.g. deca-hydronaphthalene oramides free of active hydrogen atoms, e.g. NN'-dimethylacetamide.

The degree of polymerization which the polyamidc attains can becontrolled by the proportion of anionic polymerization catalyst,siloxane initiator and lactam employed. This enables block copolymers tobe prepared with any desired molecular weight for the polyamidesegments. Theeonfiguration of the block copolymer will depend on thenumber and disposition of the X'Y radicals in the organosiloxanereactant.

The block copolymers of this invention find application as additives forincorporation in polyamides to modify the processing and otherproperties thereof. Thus, the ABA copolymers of this invention whenincorporated into nylon, preferably in amounts of from 0.1 to 5 percentby weight, provide the nylon polymer with a durable low energy surfacehaving a low coefficient of friction. Copolymers of the BAB type havingsuitable reactive terminal groups in the organosiloxane segment can beused to improve the bonding of nylon surfaces to glass. For suchapplications, the preferred block copolymers are those in which theorganosiloxane blocks have a molecular weight, of from 150 to 15,000 andare composed predominantly of dimethylsiloxane units.

The following examples illustrate the invention, and Me represents theCH radical.

EXAMPLE l Dried epsilon-caprolactam (5.7 g., 0.05 mole) was melted underargon in a flask fitted with a gas dispersion head for mixing and thetemperature raised to 120C. To the molten caprolactam was then added 4.1g. (0.001 mole) of an organosiloxane of the average formula extractedwith acetone to remove unreacted caprolac- .tam or organosiloxaneand'the residue was a polyamide-organosiloxane polyamide block copolymerhaving the average structure:

EXAMPLE 2 Epsilon-caprolactam (11.3 g., 0.1 mole) and lithium hydride(0.08 g., 0.01 mole) were stirred together under argon at 100C. When thereaction has ceased, the reaction temperature was increased to 120C andan organosiloxane (11.3 g., 0.005 mole) of the average formula wasthoroughly mixed into the molten caprolactam. The polymerization wasallowed to continue for 1 hour and the product extracted with boilingbenzene to remove unchanged starting material. The product was a blockcopolymer of the average formula In this copolymer, the cyclic terminalgroups can be opened by reaction with an amine.

EXAMPLE 3 Azacyclotridecan-Lone (lauryl lactam) (6.85 g., 0.035 mole)and an organosiloxane (2.93 g.', 0.0015 mole) of the average formulaweremixed together under argon at 170C. Sodium hydride as a 50 percentdispersion in a mineral oil'- (0.144 g., 0.003 mole) was then added andthe polymerization was allowed to continue for 1 hour. The product wasextracted with boiling benzene to remove unchanged starting material.The product was a block copolymer having the average formula EXAMPLE 4 Ioil (0.1 g., 0.002 mole) was added to the solution and thepolymerization was allowed to continue for 2 hours,

precipitation of the block copolymer commencing after approximately 30minutes. The solid product was filtered from the cooled reaction mixtureand was washed with hot benzene. The product was a block copolymerhaving the average formula EXAMPLE 5 Epsilon-caprolactam (11.3 g., 0.1mole) and an organosiloxane (3.73 g., 0.0033 mole) of the averageformula O=C=N(CH Si(C1-1 [OSi(C1-l (CH N= C=O were mixed together underargon at C. The catalyst, which was the sodium salt of caprolactam (0.89g., 0.0066 mole) was then added and the polymerization allowed tocontinue for 1 hour. The product was extracted with benzene to removeany unchanged starting material. The product was a block copolymerhaving the average formula That which is claimed is: l. A process forthe preparation of an organosiloxane-polyamide block copolymer whichcomprises (A) mixing l at least one lactam of the general formula Iamino groups or sulphur atoms, and Y is a radical of the formula F lLIFN :0

wherein R represents an alkylene radical having from two to carbonatoms, or Y is a functional group capable of initiating or promotingpolymerization of the lactam (1), there being at least one X'Y radicalpresent in the organosiloxane, and (3) a catalyst for the anionicpolymerization of the lactam and (B) exposing the mixture to atemperature at which polymerization of the lactam occurs.

2. A process as claimed in claim 1 wherein X represents a divalenthydrocarbon radical or a divalent radical composed of carbon, hydrogenand oxygen wherein the oxygen is present in the form of ether groups.

3. A process as claimed in claim 2 wherein X is the (CH or the CH CH(CHradical.

4. A process as claimed in claim 1 wherein the lactam isepsilon-caprolactam, lauryl lactam or a mixture thereof.

' 5. A process as claimed in claim 1 wherein the R' radicals are methylradicals and the specified X'Y radicals.

I 6. A process as claimed in claim 1 wherein the polymerization catalyst(3) comprises an alkali or alkaline earth metal or a hydride thereof.

7. A process as claimed in claim 1 wherein the polymerization of thelactam is carried out at a temperature in the range from 1 10 to 170C.

2. A process as claimed in claim 1 wherein X'' represents a divalenthydrocarbon radical or a divalent radical composed of carbon, hydrogenand oxygen wherein the oxygen is present in the form of ether groups. 3.A process as claimed in claim 2 wherein X'' is the -(CH2)3- or the-CH2CH(CH3)- radical.
 4. A process as claimed in claim 1 wherein thelactam is epsilon-caprolactam, lauryl lactam or a mixture thereof.
 5. Aprocess as claimed in claim 1 wherein the R'''''' radicals are methylradicals and the specified -X''Y radicals.
 6. A process as claimed inclaim 1 wherein the polymerization catalyst (3) comprises an alkali oralkaline earth metal or a hydride thereof.
 7. A process as claimed inclaim 1 wherein the polymerization of the lactam is carried out at atemperature in the range froM 110* to 170*C.